PECM Issue 29 2017 | Page 23

6. W HAT ARE SOME 9. PITFALLS YOU SEE END - FUTURE FROM THE INDUSTRY ’ S STANDPOINT ? USERS COMMONLY ENCOUNTERING IN EXPANSION JOINT APPLICATIONS ? H OW CAN THEY AVOID OR RESPOND TO SUCH PITFALLS ? 4. W HAT ARE SOME OF THE VARIOUS EXPANSION JOINT ACCESSORIES , AND DO THEY AFFECT FLUID CONVEYANCE ? Retainer rings should be used for all elastomer expansion joints to distribute bolting pressure evenly and prevent flange damage during tightening. The rings are installed directly against the back of the expansion joint flanges and bolted through to the mating pipe flanges. This helps to ensure that a seal is created between these flanges. Control units are recommended for most applications to prevent damage due to excessive pipe movement. These units consist of two or more control rod assemblies to minimize potential damage from excessive axial movement. They also prevent over-elongation and excessive compression if compression nuts are used. Flow liners extend service life by protecting elastomer expansion joints from abrasive materials, particularly in high-velocity applications. These liners prevent fast-flowing fluids or highly abrasive slurries from prematurely degrading the expansion joint tubes. 5. W HAT ARE SOME BEST PRACTICES YOU CAN OFFER IN THE AREAS OF SPECIFICATION , INSTALLATION AND MAINTENANCE OF EXPANSION JOINTS TO ENSURE LONG - TERM PERFORMANCE ? The service life of an elastomer expansion joint is subject primarily to